Control mechanism for lumber edger press rollers



J. A. DENTON 2,620,631

CONTROL MECHANISM FOR LUMBER EDGER PRESS ROLLERS Dec. 9, 1952 2 SHEETS-SHEET 1 Filed Feb. 7, 1950 INVENTOR. JOSEPH A. Damon ATTOQNELY 2 SHEETS-SHEET 2 J. A. DENTON l l. v n

l/l lmlll Dec. 9, 1952 CONTROL MECHANISM FOR LUMBER EDGER PRESS ROLLERS Filed Feb. 7, 1950 FIG-n. 3

. ing four'positions.

Patented Dec. 9, 19 52 UNITED STATES PATENT OFFICE CONTROL MECHANISM FOR LUMBER EDGER PRESS ROLLERS Application February -'7, 195i), Serial N 0. 1425769" 3'Claims. 1

This invention relates to improvements in control mechanism for the press rolls of a lumber edger.

At present, lumber edger press rolls are lifted by a cylinder which has a stroke long enough to lift the rolls to an established maximum height to permit lumber of the largest size capable of being handled by the edger to be fed into the edger. Positive mechanical stops have been used to cut-down the length of the-stroke when thinner lumber, such as boards or the like, is being fed to the edger. The rolls, if not lifted the maximum height, cannot drop from such height and thus damage" or mar the lumber or break the edger by the severe blow that would be delivered if the rolls dropped from such maximum height. However, these positive stops were often left in active position and as lumber of gradually increasing thickness passedthrough the edger, the press rolls: being held from raising by such stops would jam and damage the edger and/or spoil the lumher.

It is an object of this invention, therefore, to provide a control mechanism for the press rolls of a lumber edger which will lift the rolls to either an intermediate or maximum position and will not prevent the rolls from being lifted aboverr intermediate position as lumber of increasing thickness passes through the edger.

Another object of the invention is to provide a control mechanism for the press rolls of a lumber edgerwhich will supply downward acting lumberengaging pressure'when needed in addition to the weight of the rolls.

These objects are obtained by providing a dual acting control cylinder having amaster piston attached to a piston rod and movable from the;-

lower end to the upper'end' of the cylinder to lift the press rolls to maximum position and a secondary floating piston movable from the lower end of the cyiinder'to an intermediate'part of the cylinder to carry the master piston and the press rolls to intermediate position. Such movements are controlled by a manually operated valve hav- In the pressure'down position themaster piston is downwardly urged to the lower end of the cylinder and supplements the action of gravity in pushing the rolls down on the lumber. In the offor gravity position of the valve the cylinder is vented to atmosphere and no fluid pressure is asserted on either piston.

Gravity then supplies the entire force urging the" press rolls into contact. with the lumber. In the low lift-or intermediate position of the valve fluid pressure issupplied to the under side of the secondary pistonto urge it to the intermediate position. carrying -the master piston and piston rod 2 with it to lift the press rollsto intermediate position. When in this position, if lumber of greater thickness than normal for this intermediateposition passes under therolls, the rolls will be lifted thereby as there is only a one way connection between such rolls and the-secondary piston. 'In the high lift or maximum position of the valve fluid pressure is supplied to the lower sideof the master piston to urge it to the high position carrying the rolls to their high lift or maximum position. The valve is arranged to move in one direction from off position to pressure down position and in an opposite direction from off position to intermediate and high positions. Thus" the pistons must be moved to intermediate position as the valve is moved to and from high position. This causes the dropping or downward movement of the rolls to be checked at intermediate position and thuslessens any blow delivered thereby if they are dropped from high position on to lumber thin enough to enter under therolls when in intermediate position. h

Thenovelfeatures, which are considered characteristicof the invention, are set forth with particularity in the appended claims. The invention itself, however, both as to its orgini' zation and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment when readin connection with the accompanying drawings, inwhich;

Fig. 1 is a fragmentary view partly in side eleration and partly in section of a lumber edger having press roll control mechanismembodying the present, invention, the pressure down position of the control valve being shown in solid lin and the pressure off position thereof being shown in broken line, thefully down position of the press rolls being shown in solid line at the left and the intermediate and fully up position of suchrolls being'shown in broken line;

Fig. 2 is an enlarged fragmentary view. partly in elevation and partly in section of the control mechanism for the press rolls, with the parts shown in low liftv or intermediate position; and Fig. 3 is a view similar to that of Fig. 2 with the parts shown in high lift or maximum position.

Referring to the drawings by reference numerals, the lumber edger, indicated generally at H), is of well-known design. It has a frame l2 in which is pivotally mounted a. pair of press roll frames. [4 rotatably carrying press rolls [6. The press rolls have a, fully down positionshown in full line at the left of Fig. l and, are normally urged by gravity toward that positionto, press lumber against the driven feeder rolls. 2 8 and thereby pass the lumber to the-cutting saws, and

out the other side of the edger. The press roll frames and press rolls are lifted to an intermediate position indicated in broken line at I and to a maximum position indicated in broken line at M by press roll connecting rods it connected to a vertically reciprocal cross head 28. The cross head 20 is mounted in a cross head guide 22 and is operated by the piston rod 24 of a dual acting cylinder indicated generally at 26. When the piston rod 24 is raised the press rolls iii are lifted. When relatively thick lumber is being fed to the edger the rolls I6 are first raised to maximum position and the lumber positioned between such press rolls and power-operated feeder rolls 28. With the lumber so positioned the press rolls [6 are then dropped onto the lumber. If relatively thin lumber, such as boards, are to be run through the edger, then the press rolls 16 are raised to the intermediate position and then dropped on the lumber to press it against the feeder rolls.

The dual acting cylinder 26, which controls the lifting, the dropping of the press rolls, and the application of pressure downwardly thereon, is mounted on the top of frame I2. It has a large diameter short bore 30 at its lower end interconnected with a small diameter long bore 32 at its upper end. The upper bore 32 has an inlet and outlet port 44 at its upper end, such port being spaced below the top of the bore to provide a cushion chamber bled by a small channel 45. The lower bore 30 has an inlet and outlet port 56 at its bottom. An inlet and outlet port 52 is positioned at the juncture of the two bores. A master piston 34 operable in the upper bore 32 partly projects into the lower bore 36 in the down position thereof. It is connected to the piston rod 24 to provide vertical reciprocal movement thereto. A secondary floating piston 36 is operable within the bore 30 and its movements are limited by the length of such bore. Both of the pistons have offsets 38 at their bottoms to provide space for the admission of fluid pressure to the lower side of piston 34 when such pistons are in contact at the intermediate position and to the lower side of piston 36 when in fully down position.-

In the normal operating position all ports are connected with exhaust and the floating iston 36 drops to its lowest position in the cylinder 4 (see Fig. 1). The piston 34 and rod 24 will either be fully down (see Fig. 1) or will be raised within the cylinder to the position determined by the thickness of lumber passing between the feed rolls 28 and the press rolls I6. In some instances a it is necessary to a ply pressure down against the press rolls Hi. This is accomplished by supplying fluidpressure through port 44 to the top of the piston 34 at the same time connectlng ports 52 and 56 to atmosphere. When relatively thin lumber is to be fed to the edger the press rolls I6 are first lifted to intermediate position ;by fluid pressure applied to the under side of 1 floating piston 36 through port 55. It is raised ,to the position shown in Fig. 2 carrying with it the piston 34 and iston rod 24. This lifts the ,press rolls l6 tothe position indicated at I in Fig. 1. After the lumber is set under such rolls the fluid pressure is cut off and the rolls drop down on the lumber. If such lumber should increase in thickness. as it passes throu h the edger the press rolls will risecarrying the piston 34 and rod 24 upwardly. However, there is nothing other than the force of gravity to restrain such upward movement even when the intermediate position is reached. When it is desired to lift the press rolls I6 to high lift or maximum position to receive relatively thick lumber, fluid pressure is applied through port 52 to the bottom of the piston 34 forcing it to the position shown in Fig. 3. If the piston 34 should at that time be stationed below the port 52 the fluid pressure would first enter through port 56 to cause piston 36 to raise piston 34 to the port 52.

The control of fluid pressure to the proper ports of the double acting cylinder 26 is accomplished by a four position manually operated control valve 40. This valve has a cylindrically shaped chamber 68 with: a passage 42 leading to the port 44; a passage 46 leading to an atmospheric exhaust 48; a passage 58 leading to the port 52; a passage 54 leading to the port 56; and a passage 58 leading to a source of fluid under pressure. A vane 62 is rotatably mounted in the cylindrical chamber 68 and its rotation is controlled by n outside lever 64. A rod 66 may lead from such lever to a conveniently positioned operator station. When the lever 64 is moved counter-clockwise from the position shown in broken line to the position shown in full line of Fig. 1, fluid pressure enters passage 42 through port 44 to the upper surface of piston 34. At the same time passages 58 and 54 are vented to exhaust 48. When the lever 64 is moved clockwise from such full line position to the position shown in broken lines in Fig. 1, the passage 58 from the source of fluid pressure is closed and the passages 42, 50 and 54 are all connected to exhaust 48. In this position only gravity acts to force the press rolls 56 toward the feeder rolls 28. Further clockwise rotation of the lever 64 moves the vane 52 to the position shown in Fig. 2. In this position fluid pressure is transmitted from the passage 58 to the passage 54 through port 55 to the under side of secondary piston 36 causing it to be raised to the intermediate position shown in Fig. 2. In this position ports 44 and 52 are connected to the exhaust 48 so that the piston 34 is still free to move upwardly and downwardly within its limits above the intermediate position. This permits the press rolls to freely rise or drop as lumber of thickness greater than that accommodated by the intermediate position of the rolls passes thereunder. When the lever 54 is further rotated in clockwise direction to the position shown in Fig. 3 the vane 62 connects the passage 58 to both the passages 58 and 54 and the ports 52 and 56. The port 44 remains connected by passage 42 to the exhaust 48. This supplies fluid pressure to the bottom of piston 34 forcing it to the maximum lift position shown in such figure. After the piston 34 has opened the port 52, pressure will be applied to both the upper and lower surfaces of piston 36 and it will through its own weight move to the low position shown without any effect, however, on the position of the piston 34.

To allow the press rolls to drop from maximum height, the lever 64 must pass through the intermediate position shown in Fig. 2 before reaching the off position shown in the broken line of Fig. 3. Because of this the piston 36 is momentarily raised and automatically checks the lowering of piston 34 with a consequent break in the fall of the press rolls [6. An operator controlling the operation of the valve 40, therefore, does not have to exercise unusual care in selecting either the intermediate or high lift position before inserting lumber between the press rolls l6 and feed rolls 28. If by chance he should select the upper lift position for lumber which needed only an intermediate lift for proper clearance, then the rolls would not drop directly on such lumber from the full height when released by the valve. In the event tapered pieces of lumber are being fed through the edger, the rolls l6 will be lifted by such lumber beyond intermediate position without any preliminary action on the part of the operator, such as the removal of intermediate stops. If it becomes necessary to add more downward pressure than supplied by gravity to continue the feeding of the lumber or to momentarily hold one end of lumber as it is started into the edger, the operator need only swing the control lever 64 counter-clockwise to the pressure down position. Even in this position, if the lumber should increase in thickness, the rolls l6 can still be lifted against such down pressure without mechanical damage to the edger.

Although only one embodiment of the invention is shown and described herein, it will be understood that this application is intended to cover such changes or modifications as come within the spirit of the invention or scope of the following claims.

I claim:

1. A control mechanism for the press roll of a lumber edger or for other devices in which a heavy element must be raised, lowered by gravity to an intermediate momentarily stopped position, and urged downwardly under fluid pressure while working, comprising a dual acting fluid pressure cylinder having a bottom and a top, a master piston operable in the upper part of said cylinder, a piston rod connected to said master piston, said rod extending through said top and adapted to be connected to a press roll or other heavy element, a secondary piston operable in the lower part of said cylinder, an upper port communicating with the top of said cylinder to direct fluid pressure to the top of said master piston to apply downwardly directed working pressure, a lower port communicating with the bottom of said cylinder todirect fluid pressure to the bottom of said secondary piston to raise said secondary piston to an intermediate momentarily stopped position, an intermediate port communicating with said cylinder at a distance above the bottom of said cylinder greater than the total thickness of said secondary piston and less than the sum of the total thicknesses of said secondary piston and said master piston to prevent the top of said master piston from being below said intermediate port when both pistons are at their lowest position in said cylinder whereby the bottom of said master piston may slide below said intermediate port, valve means having a first port communicating with said upper port, a second port communicating with said intermediate port, a third port communicating with said lower port, a fourth port communicating with atmosphere and a fifth port communicating with a source of fluid pressure, said valve means including movable means having a first position interconnecting said first and fifth ports and interconnecting said second, third, and fourth ports to apply downwardly directed working ressure on said master piston, said movable means having a second position interconnecting said first second, third, and fourth ports and closing said fifth port to let gravity urge both said pistons downwardly of said cylinder, said movable means having a third position interconnecting said third and fifth ports and said first, second, and fourth ports to apply upward pressure on said secondary piston to move said secondary piston to said momentarily stopped position and let said master piston drop by gravity to said momentarily stopped position, said movable means interconnecting said second, third, and fifth ports and interconnecting said first and fourth ports to apply upwardly directed pressure on said master iston and let it move to the top of said cylinder, said movable means being unable to move from fourth to second or first positions without passing through said third position, and a source of fluid pressure connected with said fifth port.

2. A control mechanism for an element biased in one direction by gravity, comprising a source of fluid pressure, valve means connected with said source, said valve means having first, second and third ports for connection with a pressure cylinder and an escape port connected to atmosphere, a fluid pressure cylinder having an upper port connected to said first port, an intermediate port connected to said second port and a bottom port connected to said third port, a piston movable in said cylinder from an upper position adjacent said upper port to a lowermost position adjacent said bottom port, said piston in said lower position having its bottom below and its top above said intermediate port, a piston rod connected to said piston extending from said cylinder and adapted to be connected with said element, and movable means associated with said valve means and having a first extreme position in which said movable means interconnects said source with said first port to apply pressure to the top of said piston, said movable means having a second extreme position in which said movable means interconnects said source with said second and third ports, said movable means having at least one other position intermediate said extreme positions'in which said movable means interconnects said first and second ports with said exhaust port and said source with said third port whereby the downward motion of said piston under the influence of gravity is momentarily arrested with the bottom thereof at said intermediate port, said movable means being unable to pass from one to the other of said extreme positions without going through said intermediate position.

3. A control mechanism as claimed in claim 2 in which there is a floating piston in said cylinder operable between said bottom port and said intermediate port, there being abutment means to limit the upward movement of said floating piston so that in its uppermost position the top of said piston is below said intermediate port whereby when said movable means is in said intermediate position fluid pressure from said source will not escape through said intermediate port.

JOSEPH A. DENTON.

REFERENCES CITED The following references are of record in the file of this patent:

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